References have been noted to piperazinyl compounds (and ethers thereof); aryl- or aralkyl-substituted piperazinyl ether, hydroxyl or nitrile compounds, and piperazinyl ester derivatives, some of which have biological activity. Acylhydroxamic acid derivatives have been described in the literature including pyridinium and piperidinium derivatives.
No reference to piperazinyl, particularly aryl- or aralkyl-piperazinyl, derivatives of acylhydroxamic acids has been noted, except the one non-aromatic compound N,N'-piperazinyl-bis-(isoproprionohydroxamic acid) reported in Jour. Medicinal Chem., Volume 12, page 940 (1969) by R. T. Coutts et al. The only significant biological activity found for this latter compound was a hypotensive effect.